The present invention relates to a semiconductor device and, more particularly, to a semiconductor device having therein an analog/digital conversion (hereinbelow, A/D conversion) circuit.
An example of a semiconductor device having therein an A/D conversion circuit is a microcomputer (hereinbelow, also called CPU). In recent years, the speed of a CPU is increasing. The number of functions provided for a CPU is also increasing and a CPU has multiple functions.
On the other hand, it is undesirable to increase external terminals (pins) of a semiconductor device as a CPU from the viewpoint of reduction in size and weight and/or lower price of an electronic device having the CPU. For reduction in the number of pins of a semiconductor device, it is becoming difficult to assure, in the semiconductor device, a dedicated input pin for supplying an analog signal to an A/D conversion circuit from the outside of the semiconductor device. Consequently, for example, a pin used for another function and an input pin of the A/D conversion circuit are made common. In this case, for example, a selector for switching is coupled between the common pin and the A/D conversion circuit.
Patent Literature 1 discloses an A/D conversion circuit capable of suppressing decrease in a dynamic range while improving the A/D conversion characteristic.